There has been traditionally known a phenomenon in which, when starting and stopping of an engine are repeated, vapor of the blowby gas leaking out from a combustion chamber liquefies due to insufficient warming up of the engine. Further, it is also known that the engine oil is deteriorated, if the blowby condensate water generated by this liquefaction mixes into an engine oil (e.g., see Patent Literature 1, hereinafter PTL 1).
To address this issue, the engine of PTL 1 stops the cooling water pump in the early stage of the operation, to avoid cooling of the engine. This induces an increase in the temperature of the engine, which restrains cooling of the blowby gas and restrains generation of the blowby condensate water.